1. Field of the Invention
The present invention relates to a frequency modulation (FM) receiver. More particularly, the present invention is preferably applicable to a method by which a pulse noise generated by an arctangent detector can be reduced.
2. Description of the Related Art
Some FM receivers include arctangent detectors to demodulate FM received signals (Japanese Patent Application Laid-open No. H6-77734). An in-phase component and a quadrature component perpendicular to each other obtained from an FM received signal are input to the arctangent detector. The arctangent (arctan) calculation of the ratio between the in-phase component and the quadrature component is performed, and the derivative value of the result of the calculation is output as a demodulated signal.
The arctangent detector generates a pulse noise when a weak electric field signal having a poor S/N ratio is input thereto. Therefore, in a conventional FM receiver, an output from the arctangent detector is passed through a low-pass filter, thereby removing such a pulse noise.
In a method by which a pulse noise is removed by using a low-pass filter, however, a high-frequency signal component that is fundamentally necessary is also removed. Therefore, an audio signal reproduced by an FM receiver may be deteriorated.